Source : Webster's Revised Unabridged Dictionary (1913)

Rash \Rash\, v. t. [For arace]
   1. To pull off or pluck violently. [Obs.]

   2. To slash; to hack; to slice. [Obs.]

            Rushing of helms and riving plates asunder.
                                                  --Spenser.

Rash \Rash\, n. [OF. rashe an eruption, scurf, F. rache; fr.
   (assumed) LL. rasicare to scratch, fr. L. radere, rasum, to
   scrape, scratch, shave. See {Rase}, and cf. {Rascal}.] (Med.)
   A fine eruption or efflorescence on the body, with little or
   no elevation.

   {Canker rash}. See in the Vocabulary.

   {Nettle rash}. See {Urticaria}.

   {Rose rash}. See {Roseola}.

   {Tooth rash}. See {Red-gum}.

Rash \Rash\, n. [Cf. F. ras short-nap cloth, It. & Sp. raso
   satin (cf. {Rase}); or cf. It. rascia serge, G. rasch,
   probably fr. Arras in France (cf. {Arras}).]
   An inferior kind of silk, or mixture of silk and worsted.
   [Obs.] --Donne.

Rash \Rash\, a. [Compar. {Rasher}; superl. {Rashest}.] [Probably
   of Scand. origin; cf. Dan. & Sw. rask quick, brisk, rash,
   Icel. r["o]skr vigorous, brave, akin to D. & G. rasch quick,
   of uncertain origin.]
   1. Sudden in action; quick; hasty. [Obs.] ``Strong as
      aconitum or rash gunpowder.'' --Shak.

   2. Requiring sudden action; pressing; urgent. [Obs.]

            I scarce have leisure to salute you, My matter is so
            rash.                                 --Shak.

   3. Esp., overhasty in counsel or action; precipitate;
      resolving or entering on a project or measure without due
      deliberation and caution; opposed to prudent; said of
      persons; as, a rash statesman or commander.

   4. Uttered or undertaken with too much haste or too little
      reflection; as, rash words; rash measures.

   5. So dry as to fall out of the ear with handling, as corn.
      [Prov. Eng.]

   Syn: Precipitate; headlong; headstrong; foolhardy; hasty;
        indiscreet; heedless; thoughtless; incautious; careless;
        inconsiderate; unwary.

   Usage: {Rash}, {Adventurous}, {Foolhardy}. A man is
          adventurous who incurs risk or hazard from a love of
          the arduous and the bold. A man is rash who does it
          from the mere impulse of his feelings, without
          counting the cost. A man is foolhardy who throws
          himself into danger in disregard or defiance of the
          consequences.

                Was never known a more adventurous knight.
                                                  --Dryden.

                Her rush hand in evil hour Forth reaching to the
                fruit, she plucked, she eat.      --Milton.

                If any yet to be foolhardy To expose themselves
                to vain jeopardy; If they come wounded off, and
                lame, No honors got by such a maim. --Hudibras.

Rash \Rash\, v. t.
   To prepare with haste. [Obs.] --Foxe.

Source : WordNet®

rash
     n 1: any red eruption of the skin [syn: {roseola}, {efflorescence},
           {skin rash}]
     2: a series of unexpected and unpleasant occurrences; "a rash
        of bank robberies"; "a blizzard of lawsuits" [syn: {blizzard}]

rash
     adj 1: imprudently incurring risk; "do something rash that he will
            forever repent"- George Meredith
     2: marked by unthinking boldness; with defiant disregard for
        danger or consequences; "foolhardy enough to try to seize
        the gun from the hijacker"; "became the fiercest and most
        reckless of partisans"-Macaulay; "a reckless driver"; "a
        rash attempt to climb the World Trade Center" [syn: {foolhardy},
         {reckless}]